The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
U.S. Pat. No. 5,368,312 describes a sealing arrangement for the sealing-off of metallic cylindrical bodies, particularly for shafts in cryogenic valves which are surrounded by an essentially ring-shaped sealing device which cannot be glued to metal. The sealing device is surrounded by a ring which is arranged concentrically with respect to the shaft, consists of a metal alloy with shape memory characteristics and with a one-way characteristic and the interior shape of which is adapted to the exterior shape of the sealing device and which contracts when the transition temperature is exceeded.
U.S. Pat. No. 6,354,566 describes live loaded valve stem packing wherein grafoil packing is molded into a metal cap that prevents extrusion of the packing, and has live loading built into the metal cap. This metal cap may be conventional flat spring materials or a shape memory alloy. The cap is designed with a singular hump, entirely along its top surface. On this hump there are two slots through the hump, 180 degrees apart, for ease of removing the packing. Upon assembly of the packing box, the hump is elastically flattened out due to axial loading through the fasteners. As the packing consolidates during service the hump deflects to maintain a relatively constant or enhanced axial load on the packing to enhance sealing, even during a fire.
United States Publication No. US 2014/0150879 describes a valve actuator, valve, and method of actuation of a valve. The valve actuator includes a shape memory alloy element attachable to a valve body, capable of use with a valve to cause movement of the valve between first and second positions at a predetermined temperature and responsive to at least a threshold amount of temperature change of the shape memory alloy element. The valve actuator further includes an expansion element attached to the shape memory alloy element, the expansion element responsive to temperature changes at a rate lower than a rate of change of temperature indicative of a valve leak, the expansion element adjusting tension on the shape memory alloy element, thereby changing the predetermined temperature.